Angular2 manually implement change detection using ApplicationRef

Question

Getting a change detection error

Expression has changed after it was checked. Previous value: 'true'. Current value: 'false'

so I want to manually run another round of change detection. Found information about using ApplicationRef.tick() but currently getting error

ERROR in [default] C:\development\SolarUI11\src\app\update\update.component.ts:8 :11 Argument of type '{ selector: string; styles: any[]; template: any; providers: ( typeof ApplicationRef | typeof Date...' is not assignable to parameter of type ' Component'. Types of property 'providers' are incompatible. Type '(typeof ApplicationRef | typeof DatePipe)[]' is not assignable to type 'Provider[]'. Type 'typeof ApplicationRef | typeof DatePipe' is not assignable to type ' Provider'. Type 'typeof ApplicationRef' is not assignable to type 'Provider'. Type 'typeof ApplicationRef' is not assignable to type 'FactoryProvide r'. Property 'provide' is missing in type 'typeof ApplicationRef'.`

I think I'm just stuck on the syntax of implementing this, couldn't find enough information myself to be able to use it.

Typescript:

import { Component, Input, ApplicationRef } from '@angular/core';
import { FormGroup, FormBuilder, Validators } from '@angular/forms';
import {NgbDateStruct} from '@ng-bootstrap/ng-bootstrap';
import {DatePipe} from "@angular/common";
import { DataTable } from '../data/datatable';
import { DPS } from '../data/datainfo.ts';

@Component({
  selector: 'update-validation',
  styleUrls: ['../app.component.css'],
  templateUrl: 'update.component.html',
  providers: [DatePipe, ApplicationRef]
})
export class UpdateComponent {
  @Input() receivedRow:DataTable;
   public dt: NgbDateStruct;
   public dt2: NgbDateStruct;
   public startCheck: boolean = false;
   public endCheck: boolean = false;
   updateForm : FormGroup;

   constructor(fb: FormBuilder, private datePipe: DatePipe, private appref: ApplicationRef){
     this.updateForm = fb.group({
      'dataPoint' : [null, Validators.required],
      'ICCP' : [null, Validators.required],
      'startDate' : [null, Validators.required],
      'endDate' : [null, Validators.required]
      }, {validator: this.endDateAfterOrEqualValidator})
   }

 ngOnChanges(){
if(this.receivedRow){
  this.updateForm.controls['dataPoint'].setValue(this.receivedRow.tDataPoint);
  this.updateForm.controls['ICCP'].setValue(this.receivedRow.tICCP);
  this.updateForm.controls['startDate'].setValue(this.receivedRow.tStartDate);
  this.updateForm.controls['endDate'].setValue(this.receivedRow.tEndDate);
  }
}

  resetForm(){
    location.reload();
    //this.updateForm.reset();
  }

  submitForm(value: any, originalRow: any){
    var dataPointID = originalRow.receivedRow.tDataPoint;
    for (let entry in DPS) {
      if (DPS[entry].tDataPoint === dataPointID) {
        DPS[entry].tDataPoint = String((<HTMLInputElement>document.getElementById("dataPoint")).value);
        DPS[entry].tICCP = String((<HTMLInputElement>document.getElementById("ICCP")).value);
        DPS[entry].tStartDate = String((<HTMLInputElement>document.getElementById("startDate")).value);
        DPS[entry].tEndDate = String((<HTMLInputElement>document.getElementById("endDate")).value);
      }
    }
  }

  getStartDate(){
    var month = this.receivedRow.tStartDate.substring(0,2);
    var day = this.receivedRow.tStartDate.substring(3,5);
    var year = this.receivedRow.tStartDate.substring(6,10);
    var dateToUse = new Date(Number(year),Number(month)-1,Number(day));
    let timestamp = this['startDate'] != null ? new Date(this['startDate'].year, this['startDate'].month-1, this['startDate'].day).getTime() : dateToUse.getTime();
    this.updateForm.controls['startDate'].setValue(this.datePipe.transform(timestamp, 'MM/dd/yyyy'));
    this.appref.tick();
  }

  getEndDate(){
    var month = this.receivedRow.tEndDate.substring(0,2);
    var day = this.receivedRow.tEndDate.substring(3,5);
    var year = this.receivedRow.tEndDate.substring(6,10);
    var dateToUse = new Date(Number(year),Number(month)-1,Number(day));
    let timestamp = this['endDate'] != null ? new Date(this['endDate'].year, this['endDate'].month-1, this['endDate'].day).getTime() : dateToUse.getTime();
    this.updateForm.controls['endDate'].setValue(this.datePipe.transform(timestamp, 'MM/dd/yyyy'));
    this.appref.tick();
  }

  public showDatePick(selector):void {
     if(selector === 0) {
       this.startCheck = !this.startCheck
     } else {
       this.endCheck = !this.endCheck;
     }
  }

  endDateAfterOrEqualValidator(formGroup): any {
    var startDateTimestamp, endDateTimestamp;
    for(var controlName in formGroup.controls) {
      if (controlName.indexOf("startDate") !== -1) {
       startDateTimestamp = Date.parse(formGroup.controls[controlName].value);
      }
      if (controlName.indexOf("endDate") !== -1) {
        endDateTimestamp = Date.parse(formGroup.controls[controlName].value);
      }
    }
    return (endDateTimestamp < startDateTimestamp) ? { endDateLessThanStartDate: true } : null;
  }
}

Adler

Answer 1

import { Component, Input, ChangeDetectorRef } from '@angular/core';

Inject

constructor(private cdRef:ChangeDetectorRef) {}

and use it

public showDatePick(selector):void {
  if(selector === 0) {
    this.startCheck = !this.startCheck
  } else {
    this.endCheck = !this.endCheck;
  }
  this.cdRef.detectChanges();
}

Just

that actually fixed the second error, not the first. Do I simply insert private cdRef:ChangeDetectorRef into my already existing instructor or is there some sort of inject syntax I include? – Adler

Perhaps you need to add this.cdRef.detectChanges() at other places as well. Your question contains too much code. I didn't fully investigate. – Enhance

You haven't explained why we are not using ApplicationRef. Is that obsolete now? – Knowhow

ApplicationRef.tick() is somehow similar but runs change detection for the whole application. If this is not necessary, it's better to avoid it. If a component has ChangeDetectionStrategy.OnPush configured, ApplicationRef.tick() would still skip this component for change detection and therefore wouldn't solve the problem. – Enhance

Answer 2

Have you tried using ChangeDetectorRef?

constructor(private changeDetector: ChangeDetectorRef) {
}

And detect the changes with

changeDetector.detectChanges();

Brought